Conductive Post Transducer Connections for IVUS Signal Integrity

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Solution Overview

Problem

Intravascular Ultrasound (IVUS) transducers face challenges in achieving low resistance and robust electrical connections, particularly due to the micron-scale operation, sterilization compatibility, and high-speed rotation within varying anatomy, where existing connections are prone to signal loss and cracking during sterilization.

Innovation Solution

The implementation of a conductive post embedded within the passive layer of the transducer, providing direct low-resistance electrical connections with exposed surfaces for side or bottom access, and an extension substrate to protect the active element from thermal stress during high-temperature connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If electrical connections are made through housing and backing layer in conventional transducers, then the transducer structure is simple, but the connection resistance is high and signal loss occurs

Engineering Contradiction:
Improvesignal lossVSAvoidconnection structure complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The connection structure is segmented into distinct functional components: a conductive post for low-resistance electrical connection, an extension substrate for mechanical support and thermal management, and a backing layer for acoustic damping. This segmentation allows each component to be optimized for its specific function, reducing overall signal loss while maintaining structural integrity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The conductive post extends vertically through the backing layer thickness, creating a three-dimensional connection path that bypasses the limitations of planar connections through the housing. This vertical dimension provides a direct low-resistance path from the piezoelectric element to the external circuit, significantly reducing signal loss compared to conventional lateral connections.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If conventional connections are used, then manufacturing is simpler, but connections are prone to cracking during sterilization

Engineering Contradiction:
Improveconnection robustnessVSAvoidconnection manufacturing ease
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The conductive post is embedded within the backing layer during the manufacturing process, establishing a robust electrical connection before the transducer undergoes sterilization. This preliminary establishment of the connection ensures that the critical electrical path is already in place and protected, preventing cracking that would occur if connections were made after sterilization when materials are more brittle.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The connection structure uses composite materials: a metal conductive post embedded in a polymer or epoxy backing layer, with an extension substrate providing additional mechanical support. This composite structure combines the electrical conductivity of metal with the mechanical flexibility and thermal resistance of polymers, creating a connection that can withstand sterilization temperatures and mechanical stresses without cracking.

Inventive Principle:
Principle #40Composite materials

3Loss of energy

If direct electrical connections are made to piezoelectric elements, then signal loss is reduced, but thermal stress during high-temperature connections may damage the active element

Engineering Contradiction:
Improvesignal lossVSAvoidthermal stress on active element
Core Design Contradiction:
Loss of energyVSTemperature

Solution Approach 1:

The extension substrate acts as an intermediary between the conductive post and the piezoelectric element. During high-temperature connection processes, the extension substrate absorbs and dissipates thermal stress, protecting the sensitive piezoelectric element from direct thermal exposure. This intermediary structure allows direct electrical connection to be made while isolating the active element from damaging temperatures.

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution reduces signal loss and enhances connection robustness, allowing the transducer to withstand sterilization and maintain performance in demanding IVUS applications.

Implementation Method 1

a conductive post embedded in the passive layer to provide a direct low resistance electrical connection to the acoustic element

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

the active element converts electrical energy into mechanical energy to generate ultrasound waves

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

vice versa to sense ultrasound waves

Methodology Applied
Scientific EffectPiezoelectric effect: Converse Piezoelectric Effect

Implementation Method 4

The extension substrate protects the acoustic element from thermal stress when a connection is made to the electrode at high temperatures

Methodology Applied
Scientific EffectThermal stress protection: Thermal Shock

Data Source

PatentEP2238588B1Connections for ultrasound transducers
Publication Date: 2020.09.23 BOSTON SCIENTIFIC SCIMED INC
  • EP2238588B1 patent drawingFigure 1(a)~1(b)
  • EP2238588B1 patent drawingFigure 2~3
  • EP2238588B1 patent drawingFigure 4A~4B

AI summary

Described herein are electrical connections to acoustic elements, e.g., piezoelectric elements. In an exemplary embodiment, a transducer comprises an acoustic element, a passive layer attached to the acoustic element, and a conductive post embedded in the passive layer to provide a direct low resistance electrical connection to the acoustic element. In one embodiment, the conductive post has an exposed side surface allowing electrical connections to be made from the side of the transducer. In another embodiment, the conductive post has an exposed bottom surface allowing electrical connections to be made from the bottom of the transducer. In another embodiment, the transducer comprises an extension substrate adjacent to the acoustic element for protecting the acoustic element from thermal stress when a connection is made to the transducer at high temperatures. In one embodiment, a circuit is integrated on the extension substrate to process signals to or from the acoustic element.